Specific aims and methodology: 1. To conduct a sib analysis of adult females in four ecologically overlapping species of Drosophila from Southwestern Ohio. This analysis would be patterned after the analysis of Rose and Charlesworth (1981b) and would be a partial test of the generality of their conclusion that in D. melanogaster there is considerable genetic variability for the life history characters longevity, and fecundity. 2. To determine whether the antagonistic pleiotropic relationship between longevity and fecundity observed by Rose and Charlesworth in D. melanogaster, which supports the pleiotropy theory of the evolution of senence, occurs in other species as well. This would be done by comparing the longevities and early fecundities of the four species to see if the antagonistic relationship observed by Rose and Charlesworth exists in natural populations. In addition, it will be observed whether selection for increased longevity in these species has the correlated antagonistic result of decreasing early fecundity as it does in D. melanogaster. Health Relatedness: While the health relatedness of this project may not be immediately apparent The NIH itself has underscored the importance of using Drosophila as a model system to enhance our understanding of the phenomenon of aging. It is hoped that some characteristics of the aging process in Drosophila will apply to humans as well.